olson@endor.harvard.edu (Eric K. Olson) (12/07/89)
[Posted for a friend. Please reply to seth@vax.ftp.com.]
Greetings folks.
I noticed something during the last launch and was wondering if
anyone else saw it. It seemed pretty obvious to me and I was waiting
to see someone else post it, but no post.
I've played the tape about 100 times in every conceivable mode (slow,
forward, backward, still frames, color, b+w). I didn't want to post
this but it's been a bug in my...
Ok, the most recent launch of the shuttle, between about 80,000 feet and
about 110,000 feet. The bottom of the external tank looks like it's,
um, "flaming". I hope I'm wrong. I'd like to be told it's just a heat
shield burning off, or some excess hydrogen burning in the SRB flame.
Even just ice crystals falling off the tank and being illuminated by the
flames from the engines.
I know it was a night launch and we're probably seeing things we don't
normally see during the day, but *hey*.
Can someone check their tapes and tell me what they see?
Here's the timeline from the tape as broadcast on CNN. They had the
NASA feed in a little box on the screen with generated numbers
indicating (very) approximate altitude and speed and (seemingly
accurate) time since lauch:
Funny symbols:
* = updated by CNN every 3-5 seconds, not very accurate.
** = left SRB as I mean it is from behind, tail pointing up.
Disclaimer: The word "flames" is used below to indicate the optical or other
effect which is unknown by me at the present time. It is not
meant to foster or incite any reciprocal flames in net-readers.
The "flames" are not the kind one sees from solid boosters
(like Estes rockets and SRBs). They are more like the flame
one sees when one pours lighter fluid on a BBQ and lights it.
comment #
(see below) time speed* altitude(feet)*
-------------------------------------------------
1 1:34.2 1,860 80,800
2 1:34.8 1,860??(sic)80,800??(sic)
3 1:35.7 2,040 89,800
4 1:38.0 2,040(sic) 89,800(sic)
5 1:43.6 2,225 94,300
6 1:49.1 2,405 109,300
comments
--------
1) First sign of increased brightness from ET bottom.
2) First sign of "flames".
3) "flames" grow, fill area between ET and "left"** SRB (closest to camera).
4) "flames" look to be coming from the bottom of the ET and the tank-side of
the left SRB.
5) "flames" seem to stop coming from "tank-side" of "left" SRB.
6) All "flames" seem to stop as the view of the bottom of the ET and the
"left" SRB are hidden by the SRB plume.
Please. Tell me I'm wrong. Thank you.
Seth
--
seth@vax.ftp.com, ...ftp!poopsie!seth, 18 Rindge Av, Camb. Ma, 02140 USA Earthhenry@utzoo.uucp (Henry Spencer) (12/08/89)
In article <3352@husc6.harvard.edu> seth@vax.ftp.com (Seth D. Hollub) writes: >Ok, the most recent launch of the shuttle, between about 80,000 feet and >about 110,000 feet. The bottom of the external tank looks like it's, >um, "flaming". I hope I'm wrong... It's not uncommon to get some backflow of hot gases from the exhausts into the area behind the tank, especially at high altitude. (The exhaust plume from a rocket can "backflow" enough to completely envelop the rocket at high altitude, in fact.) That may be what you're seeing. Things along those lines have been seen before; they're either optical effects or just stray hot gas, by current thinking. -- 1233 EST, Dec 7, 1972: | Henry Spencer at U of Toronto Zoology last ship sails for the Moon. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
dave@viper.Lynx.MN.Org (David Messer) (12/11/89)
In article <3352@husc6.harvard.edu> seth@vax.ftp.com (Seth D. Hollub) writes: >I noticed something during the last launch and was wondering if >anyone else saw it. > >Ok, the most recent launch of the shuttle, between about 80,000 feet and >about 110,000 feet. The bottom of the external tank looks like it's, >um, "flaming". There was a long discussion of this effect after it was noticed on the first shuttle flight after Challenger (people were watching THAT one pretty closely.) Basically, what happens is that when the atmospheric pressure drops off, as the shuttle ascends, the pressure in the exhaust plume forces some of the gases forward. This will happen on any type of rocket but it is much more noticable with the shuttle because of the distance between the SRBs. Don't worry about it. -- Remember Tiananmen Square. | David Messer dave@Lynx.MN.Org -or- | Lynx Data Systems ...!bungia!viper!dave